#include <iostream>
#include <cmath>


using namespace std;


float norm_l1(float x, float y);    //declaration
float norm_l2(float x, float y);    //declaration
float (&norm_ref)(float x, float y) = norm_l1;    //norm_ref is a function reference.


int main(int argc, char **argv){
 
    cout << "L1 norm of (-3, 4) = " << norm_ref(-3.0f, 4.0f) << endl;

    return 0;
}


float norm_l1(float x, float y){
    return fabs(x) + fabs(y);
}

float norm_l2(float x, float y){
    return sqrt(x * x + y * y);
}